An optoelectronic device is arranged for converting electric energy into electromagnetic radiation, such as visible light, or vice versa. One example of an optoelectronic device is a Light Emitting Device, such as a Light Emitting Diode (LED). Light emitting devices are used to emit light by an optical surface, i.e. a light emitting surface. They typically include electrodes contacting an active area that transforms an electric current into optical energy. The electrodes connect to external contacts allowing for connecting the Light Emitting Device to an external energy source, such as a battery.
A particular example of a large-area light source is an organic light emitting device (OLED). An OLED comprises an active area including organic material to emit electromagnetic radiation. The active area is typically arranged between an anode and a cathode as electronic contacts. If a voltage is applied to the contacts, charge carriers are injected into the active area. Under the influence of the voltage drop, positive charge carriers, i.e. hole excitations (holes) injected by the anode migrate through the active area towards the cathode. Electrons injected by the cathode migrate under the influence of the voltage drop through the active area towards the anode. Within in the active area holes and electrons might eventually recombine to excitons and relax under emission of electromagnetic radiation, such as visible light.
Other examples of optoelectronic devices detect optical signals through electronic processes. These devices may be arranged as photo detectors or energy sources for converting electromagnetic radiation into electric energy, such as solar cells. They include a larger optical surface to receive and to guide optical energy to an active area.
Both types of devices are used in large-area application. Within a large-area application, it is desirous to provide for electrodes that do not cover or shade the optical surface. Furthermore, it is desirous to provide for electrodes that are easily contacted, either to an external power source or to another electronic device, such as another optoelectronic device.